This invention relates generally to the repair and/or reconstruction of machine drive elements and, in one exemplary embodiment, to a unique method and apparatus for repairing broken or worn teeth on a vehicle flywheel without having to remove the flywheel from the vehicle.
Presently, in order to repair broken or worn teeth on a vehicle flywheel, it is necessary to disconnect the vehicle transmission, and remove the flywheel for repair at another location. This is a time consuming and costly process not only in terms of the repair of the vehicle itself, but also in terms of lost opportunities as a result of not having the vehicle available for use.
There are a number of methods and associated apparatus presently utilized in the repair and/or reconstruction of damaged or broken flywheel or other type gear teeth. For example, U.S. Pat. No. 3,668,768 discloses a method of rebuilding worn gear teeth by explosive swaging.
U.S. Pat. No. 3,739,892 discloses replacement of worn teeth in a transmission by the use of an annular replacement gear which is slipped over the worn teeth after they have been ground down to a smooth annulus.
U.S. Pat. No. 3,755,877 discloses a method of repairing used gear cutter wheels including the steps of removing portions of the old, used gear teeth and welding in place metal inserts which are then machined into final tooth, form.
U.S. Pat. No. 3,548,841 describes a method of rebuilding worn teeth on members such as gears, spline shafts, sprockets, and the like by building up the clearance side of the teeth and then grinding the wear out of the worn side, and the built up portion on the clearance side until the original teeth dimensions are obtained.
All of the above described conventional techniques suffer from the significant disadvantage of having to first remove the flywheel or other gear from their operational environment before such repairs can be implemented. Of course, these techniques also require reassembly of the flywheel or other type gear which further contributes to the time and cost involved in effecting such repairs.
The present invention eliminates the major disadvantage of the above described prior art techniques by permitting damaged flywheel teeth to be repaired while the flywheel remains in place on the vehicle.
Thus, in one exemplary embodiment of the invention, repair of damaged or broken flywheel teeth may be accomplished in the following manner. The vehicle is initially positioned over a conventional lift and elevated to a raised position providing easy access to the vehicle transmission. A dust shield bolted to the transmission housing is then removed by loosening and removing four small bolts which hold it in place. Upon removal of the dust shield, a portion of the flywheel is immediately visible and easily accessible. The flywheel ring gear is then inspected to confirm an initial diagnosis of damaged or broken teeth. Once this has been confirmed, a jig or frame in accordance with this invention is mounted to the transmission housing, utilizing the pre-existing bolt holes used to retain the dust shield in place.
The jig or frame is provided with a small gear rotated about an axis parallel to the axis of rotation of the flywheel, and which is rotatable by means of a conventional socket wrench. Upon mounting the jig or frame to the vehicle transmission housing, the small "motion gear" should be in good meshing engagement with a section of teeth on the flywheel which are not in need of repair. Once this meshing engagement has been confirmed, the flywheel may be rotated by means of the socket wrench in a clockwise direction until a damaged tooth is located directly in line with an indicator on the jig. At this point, a commercially available MIG welder may be mounted on an adjustable slide mount provided on the jig through the use of a slide adapted to be secured to the welder. The jig, slide mount and slide are configured so that the welder may be adjustably located at the precise location of the damaged or broken tooth on the flywheel. By pushing the MIG welder along the slide mount, i.e., in a direction parallel to the rotational axis of the flywheel, the damaged tooth is built up or reconstructed in a fairly coarse manner, in that material over and above that which is required to form the reconstructed tooth is added at the site.
The flywheel is then rotated in the clockwise direction until the next damaged tooth comes into alignment with the indicator and this tooth is also coarsely reconstructed with the MIG welder as described above. This procedure is repeated until all damaged teeth have been reconstructed. The MIG welder and associated slide area are then removed from the slide mount on the jig.
Thereafter, a commercially available right angle die grinder fitted with an appropriate router bit is engaged within the slide mount through the utilization of another slide adapted for use with the particular die grinder employed in the process. As in the case of the welder, adjustments are permitted to insure that the die grinder router bit is properly located to make a precise cut over the built-up tooth. Pushing the die grinder along the slide mount so that the router bit moves across the tooth, i.e., in the direction parallel to the rotational axis of the flywheel, results in a restructured tooth wherein the tooth and the space on either side of the tooth are restructured to original factory specifications.
Thereafter, the flywheel is rotated in a counterclockwise direction to the next successive built-up tooth and the grinding process is repeated. This process is then repeated until all damaged teeth have been machined to their original specifications. After shutting down the cutting oil supply means (a conventional pump, for example) and the die grinder and its associated slide are removed from the slide mount and the tool jig may be removed from the transmission housing.
Upon complete repair of all of the flywheel gear teeth, as described above, the vehicle can be started several times to insure that the starter and flywheel are working properly. The dust cover or dust shield may then be reattached to the transmission housing, and the vehicle removed from the lift to thereby complete the repair process.
The invention here also relates to a novel jig or frame assembly and associated components which permit the utilization of conventional tools to effect repair of damaged or broken flywheel teeth without having to remove the flywheel from the vehicle. It will be understood that the specific manner of attachment of the jig or frame to the vehicle is dependent upon the design of the transmission housing. Thus, it will be appreciated that the jig or frame will be adapted for use with specific vehicle transmission types, manufacturers, etc. The concept, however, is the same in that the jig or frame will always be designed for attachment to existing attachment points on the vehicle enabling in situ repair of the vehicle flywheel. It may be possible, for example, to mount the jig or frame so as to obtain access to the flywheel through the starter gear opening or from any other convenient point of access to the flywheel, such as, for example, a clutch or flywheel inspection opening typically provided in all large trucks and other heavy equipment. Regardless of the specific configuration of the jig or frame, in all cases there will be provided an adjustable slide mount to accommodate a welder and a die grinder, as well as the necessary conduits to supply a cutting lubricant or oil to the repair site.
Another feature of the invention relates to the provision of an air conduit for supplying cooling air to the site after welding or, in a vacuum mode, for removing debris from the site during grinding in the event a cutting oil or fluid is not used.
The jig is also provided with means for supplying cutting oil or other fluid to the die grinding site during grinding, and in this case, since the oil or fluid will carry away the debris, the above described vacuum need not be employed.
A further feature of the invention relates to the provision of a basin or tank for recovering the cutting fluid for subsequent filtration and recirculation.
Thus, in its broader aspects, the present invention provides in a preferred exemplary embodiment a method of repairing a worn or broken machine drive element in situ comprising the steps of: a) providing a jig adapted for mounting adjacent the machine drive element in need of repair, the jig having a supporting surface provided with an adjustable slide mount assembly for supporting in sequence, a welding tool and a die grinding tool; b) mounting the jig adjacent the machine drive element in need of repair without relocating the machine drive element from its operative environment; c) attaching a welding tool on the slide mount assembly; d) welding additional material to the drive element in excess of an amount required to repair the drive element; e) removing the welding tool from the slide mount assembly; f) mounting a grinding tool on the slide mount assembly; and g) grinding excess material from the drive element with a grinding bit adapted to provide a predetermined profile to the machine drive element.
The present invention also broadly provides repair apparatus for machine drive elements comprising a jig assembly including a tool supporting surface; an adjustable slide mount assembly secured to the supporting surface for adjustment in a first direction toward and away from the supporting surface; slide means adapted to move back and forth within the slide mount assembly in a second direction substantially perpendicular to the first direction, for supporting in succession a welding tool and a grinding tool, the adjustable slide mount assembly thereby enabling working elements of the welding and grinding tools to be accurately located at a site of repair on the machine drive element.
It will be understood from the above that the invention has general applicability to the repair and/or reconstruction of other machine drive elements in addition to the above described vehicle flywheels. For example, large gears typically utilized in propulsion systems, power generation equipment and the like, periodically require repair and/or reconstruction of included gearing which involves considerable downtime and cost. The present invention addresses these concerns by providing a mechanism which can be attached directly to the gear (in the case of very large gears) or to associated housings or the like, thereby eliminating the present requirement for disassembly and/or removal of such machine drive elements from their normal operative environment.
Another exemplary use for the subject invention is in assembly lines for the production of gears and the like where, again, repair and/or reconstruction can be carried out without having to remove the gear from the assembly line, thereby achieving significant savings in time and expense. Additional applications for the invention in military, industrial and aerospace fields will also be apparent to those of ordinary skill in the art.
Other objects and advantages of the subject invention will be apparent from the detailed description which follows.